Legal claims defining the scope of protection. Each claim is shown in both the original legal language and a plain English translation.
1. A storage system comprising: a storage device which stores data; and control units each of which controls an operation for accessing said storage device, each of said control units including: a relay unit which relays access to said storage device, an access controller which selects one of a first path passing through the relay unit belonging to said control unit and a second path passing through another relay unit belonging to another control unit and accesses said storage device through the selected path when said control unit and said another control unit are in a normal operational state, and an operational-state controller which determines whether or not said another relay unit belonging to said another control unit is usable when the operational-state controller detects occurrence of an abnormality in said another control unit, and makes said another control unit transition to a partially-operational state when said another relay unit belonging to said another control unit is determined to be usable, wherein when said another control unit is in the partially-operational state, a portion of said another control unit including another access controller is not in operation and the access controller in said control unit continues to select one of the first path and the second path and access said storage device through the selected path.
A storage system manages access to a storage device. Each control unit in the system has a relay to access the storage. An access controller in each unit normally picks a path to storage: either through its own relay or through another unit's relay. If one control unit fails, its operational-state controller checks if its relay is still usable. If so, it puts the failed unit into a partially-operational state where the failed unit's access controller is disabled. The working control unit's access controller then continues accessing the storage, potentially using the still-functional relay of the partially-operational unit.
2. The storage system according to claim 1 , wherein, when said another control unit is in the partially-operational state, said access controller lowers a frequency of operations for access to said storage device through said another relay unit in said another control unit than the frequency of operations for access of when said another control unit is in a normal operational state, wherein when said another control unit is in the normal operational state, both of said another relay unit and another access controller in said another control unit are normally operating.
The storage system described previously includes the capability of the access controller to reduce the frequency of accesses to the storage device when it has to use a relay in a partially-operational control unit, compared to the frequency used when that control unit is fully operational. While the control unit is operating normally both the relay and access controller in that unit operate as designed.
3. The storage system according to claim 1 , wherein each of said control units further includes an abnormality-count storing unit which stores a count corresponding to an accumulated number of detected abnormalities for each of the relay units relaying the access, and when said access controller detects an abnormality in an attempt to access said storage device, the access controller increments the count for the relay unit through which said attempt to access is made, and reduces a frequency of use of the relay unit for accessing said storage device in correspondence with an increase in said count of the relay unit.
In the storage system, each control unit keeps track of errors for each relay it uses to access the storage device. An abnormality-count storing unit stores a count of the number of detected errors. If the access controller encounters an error while accessing the storage, it increments the error count for the relay it was using. As the error count increases for a relay, the access controller reduces how often it uses that relay to access the storage device.
4. The storage system according to claim 3 , wherein the access controller increments said count for the relay unit in a first control unit by a first addend when said access controller detects an abnormality in an attempt to access said storage device through the relay unit and the first control unit is in the normal operational state, and increments said count for the relay unit in a second control unit by a second addend when said access controller detects an abnormality in an attempt to access said storage device through the relay unit and the second control unit is in a partially-operational state, wherein the second addend is greater than the first addend.
When the access controller detects an error accessing the storage device, it increments an error counter for the relay that was being used. If the control unit containing the relay is in a normal state, the counter is incremented by a smaller value (first addend). However, if the control unit containing the relay is in a partially-operational state, the counter is incremented by a larger value (second addend), where the second addend is larger than the first addend. The storage system described in claim 3 then accesses the storage less frequently when errors increase.
5. The storage system according to claim 2 , wherein said access controller makes an attempt to access the storage device through the relay unit in one of the control units which is in a partially-operational state, after said access controller fails in an attempt to access said storage device through the relay unit in another of the control units which is in the normal operational state.
In the storage system described in claim 2, if the access controller fails to access the storage device through a relay in a control unit that is operating normally, then it will attempt to access the storage device through a relay in another control unit that is in a partially-operational state. The access controller previously lowers the frequency of access when using a relay in the partially-operational state compared to a normal operating state.
6. The storage system according to claim 1 , wherein said access controller determines the relay unit for use in access to said storage device, on the basis of a history of detection of abnormality in previous operations for access to the storage device through the relay unit.
The storage system’s access controller makes decisions about which relay to use to access the storage device based on the past history of detected errors related to accessing the storage device using that relay. The base storage system description includes two relays one from the local control unit, and one from a different control unit.
7. The storage system according to claim 1 , wherein said access controller forbids access to said storage device through said another relay unit in said another control unit according to information on detection of an abnormality in an attempt to access the storage device through said another relay unit in said another control unit, on the basis of a first criterion when said another control unit is in a normal operational state, and on the basis of a second criterion when said another control unit is in said partially-operational state, wherein the second criterion is stricter than the first criterion.
The access controller in the storage system will block access to the storage device through another control unit's relay based on error detection information. It uses different criteria for blocking depending on the state of the other control unit. When the other control unit is normal, a first (less strict) criterion is used. When the other control unit is in a partially-operational state, a second (more strict) criterion is used. The base storage system description includes two relays one from the local control unit, and one from a different control unit.
8. The storage system according to claim 7 , wherein each of said control units further includes a storage medium which stores a count corresponding to an accumulated number of abnormalities detected in an attempt to access the storage device through said another relay unit in said another control unit, and the access controller increments the count by a first addend when said access controller detects an abnormality in an attempt to access said storage device through said another relay unit in said another control unit and said another control unit is in the normal operational state, and increments the count by a second addend when said access controller detects an abnormality in an attempt to access said storage device through said another relay unit in said another control unit and said another control unit is in the partially-operational state, wherein the second addend is greater than the first addend.
Each control unit in the storage system stores a count of errors encountered when trying to access the storage device through the other control unit's relay. If an error occurs while the other unit is in a normal state, the error count is incremented by a small value (first addend). If an error occurs while the other unit is in a partially-operational state, the error count is incremented by a larger value (second addend, larger than the first addend). The access controller forbids access based on error counts as described in claim 7.
9. The storage system according to claim 1 , wherein said storage device includes a data storage and intra-storage relay units, the intra-storage relay units are respectively connected one-to-one with the relay units in said control units, and each of the intra-storage relay units relays access to the data storage from the connected relay unit, and each of said control units further includes a decision unit that makes a decision not to permit detachment of said another control unit when the decision unit receives a request for permission to detach said another control unit while said another control unit is in the partially-operational state, and the intra-storage relay unit connected to own relay unit is not in operation, and another intra-storage relay unit connected to said another relay unit in said another control unit is in operation.
The storage device in the storage system contains data storage and intra-storage relays, each connected one-to-one to the relays in the control units. Each intra-storage relay facilitates data access to the data storage from the connected control unit relay. The control units use a decision unit to prevent detachment of another control unit if it receives a detach request when the other control unit is in a partially-operational state, the intra-storage relay connected to own relay is not operating, and the intra-storage relay connected to the other control unit's relay is operating.
10. The storage system according to claim 1 , wherein each of said control units further includes a condition indicator which indicates power-supply states of the control unit, the power-supply states include a partially-operational state and an abnormal state, and the abnormal state is a state in which an abnormality occurs in said control unit and which is different from the partially-operational state.
Each control unit in the storage system has a condition indicator showing its power-supply state. These states include "partially-operational" and "abnormal". The "abnormal" state indicates a different type of failure than the "partially-operational" state. The system's base functionality involves switching to the partially-operational state when the remote relay is still usable.
11. The storage system according to claim 1 , wherein each of said control units stops power supply to said access controller when said control unit transitions to the partially-operational state.
In the storage system, when a control unit transitions to the partially-operational state, power to that unit's access controller is shut off. The base storage system description includes the ability to switch access to a remote relay when one control unit fails.
12. The storage system according to claim 1 , wherein said operational-state controller determines whether or not said another relay unit belonging to said another control unit is usable when the operational-state controller detects occurrence of an abnormality in said another control unit, and makes said another control unit transition to an inoperable state when said another relay unit belonging to said another control unit is determined to be not usable, wherein the inoperable state is a state in which a portion of said another control unit including at least said another access controller and said another relay unit is not in operation.
If the operational-state controller in the storage system determines that the other control unit's relay is not usable after an abnormality is detected in that control unit, then that other control unit is transitioned to an inoperable state. The inoperable state means that at least the other unit's access controller and relay are not in operation. The base storage system description includes the ability to use a remote relay when one control unit fails.
13. A control apparatus for controlling an operation for access to a storage device which stores data, the control apparatus comprising: a relay unit which relays access to said storage device; an access controller which selects one of a first path passing through the relay unit belonging to said control apparatus and a second path passing through another relay unit belonging to another control apparatus and accesses said storage device through the selected path when said control apparatus and said another control apparatus are in a normal operational state; and an operational-state controller which determines whether or not said another relay unit belonging to said another control apparatus is usable when the operational-state controller detects occurrence of an abnormality in said another control apparatus, and makes said another control apparatus transition to a partially-operational state when said another relay unit belonging to said another control apparatus is determined to be usable, wherein, when said another control apparatus is in the partially-operational state, a portion of said another control apparatus including an access controller is not in operation and the access controller belonging to the control apparatus continues to select one of the first path and the second path and access said storage device through the selected path.
A control apparatus manages access to a storage device by using a relay to access the storage device. An access controller picks a path: its own relay or another apparatus's relay, when both apparatus are normal. If the other apparatus fails, its operational-state controller checks if its relay is usable. If so, it puts the failed apparatus in a partially-operational state, disabling the failed apparatus's access controller. The working apparatus's access controller continues accessing the storage, possibly through the failed apparatus's relay.
14. A control method performed in a storage system which includes a storage device storing data and a plurality of control units each of which controls an operation for access to the storage device, where each of the plurality of control units includes a relay unit, an access controller, and an operational-state controller, said control method comprising: selecting, by said access controller, one of a first path passing through the relay unit in said control unit and a second path passing through another relay unit belonging to another control unit and accessing said storage device through the selected path when said control unit and said another control unit are in a normal operational state; determining, by said operational-state controller in the control unit, whether or not said another relay unit belonging to said another control unit is usable when the operational-state controller in the control unit detects occurrence of an abnormality in said another control unit; and making, by the operational-state controller, said another control unit transition to a partially-operational state when said another relay unit belonging to said another control unit is determined to be usable, wherein, when said another control unit is in the partially-operational state, a portion of said another control unit including another access controller is not in operation and the access controller belonging to the control unit continues to select one of the first path and the second path and access said storage device through the selected path.
A control method manages access to a storage device. The method selects a path: either through its own relay or through another unit's relay, when both are normal. If the other unit fails, an operational-state controller checks if its relay is usable. If so, the other unit enters a partially-operational state where its access controller is disabled. The working unit's access controller continues accessing the storage through the selected path, possibly using the other unit's relay.
Unknown
September 30, 2014
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